Device for the physicochemical separation of constituents of a fluid

ABSTRACT

Apparatus for physicochemical separation and filtering constituents of fluids having a flexible leak-tight or semipermeable casing which tightly envelopes a filter material and inlet and outlet pipes for passing a fluid through the casing in contact with the filter material. The casing is made in a flat profile that can be formed into various shapes such as spirals, ribbons or the like.

BACKGROUND OF THE INVENTION.

The invention relates to a device for separation of the constituents ofall fluids, that is to say both liquids and gases, which device operatesby a physicochemical route.

In the continuation of the description and in the claims, the term"separation" should be understood in its widest sense, that is to sayfiltration proper, but also the retention of particles, of charges, ofmicroparticles, of ions of dissolved species, ionic or otherwise,separation or immobilization. These different actions are capable ofresulting in the concentration, refining or purification of the fluidsubjected to these actions. The invention also relates to thefunctionalization of the medium during the separation, the stagepreliminary to subsequent diagnostic or working operations of thefunctionalized support.

Separation is carried out in a great many fields for diverse and variedapplications. Thus, in the very general fields of chemistry and biology,it frequently proves necessary to carry out phase concentrations,separations or purifications in the context of analysis and inindustrial processes.

To do this, recourse is commonly had either to conventional filters(disc filters, plate filters, filter presses, precoat filters), whichrequire significant filtration equipment, or to filter cartridges, whichrequire heavy molds for their manufacture. In both cases, consequentullages are generated and, moreover, such filters exhibit a partitioncoefficient which is most often unsatisfactory or limited.

For other applications, recourse is had, for the separation of ionicspecies, to ion exchange resins. Such resins are, in a known way,composed of beads and microbeads functionalized according to the type ofexchange desired.

Whatever the process of separation employed and its corollary, theequipment which enables this separation to be carried out, a certainnumber of problems remain, including the ullages generated by theequipment as well as its bulk, indeed its weight also, and itsinvestment.

Applications increasingly demand, in order to carry out a directmeasurement, a separation process capable of being carried out in linewithout an intermediate stage of collection of the fluid to be analyzed.

Moreover, the search is increasingly to increase the kinetics ofseparation, without, for all that, detrimentally affecting the resultsof this separation.

SUMMARY OF THE INVENTION.

The object of the invention is to provide a physicochemical separationdevice for all types of fluid which overcomes these disadvantages withmaximum efficiency for a minimum filter charge and which makes itpossible to carry out an in-line separation in order to carry out and toobtain, immediately, results of measurement or of analysis, whileoptimizing the kinetics of the process.

This device for the physicochemical separation of fluids is equippedwith a pipe for introduction of fluid to be filtered and with a pipe fordeparture of said fluid thus filtered and comprises, between the twopipes, a filter material based on textile fibers placed in the path ofthe fluid. The expression filter material, as used in the presentapplication, refers to any material appropriate for separation, asdefined above.

This device is characterized in that it is composed of a flexibleleaktight or semipermeable casing made of plastic which tightlyenvelopes the filter material, so as to constitute a filter with a flatprofile or capable of adopting a flat profile, the separation takingplace in the plane of the filter and with respect to the flat profile ofthe filter material.

This configuration makes it possible to enjoy a consequent separationprofile equivalent to the greater length of the medium and not to itsthickness, as in conventional filtration, for minimum bulk, charge andullage.

In other words, the invention comprises tightly enveloping a filtermaterial within a flexible plastic casing intended to restrict the pathof the fluid in the filter material without, for all that, bringingabout a preferential path, one of the results of which is an increase inthe progression of the fluid in contact with the textile fibers of thefilter material, in this way promoting leaching or contact phenomena. Inthis way, maximum efficiency of the separating power is obtained for aminimum mass.

In one embodiment of the invention, the flexible casing is tubular andis produced from a heat-shrinkable or drawable material, so as to makepossible with ease the introduction of the filter material or media intosaid casing and then to confine it by raising the temperature or by amechanical route.

According to an advantageous characteristic of the invention, theflexible leaktight or semipermeable casing is composed of two plasticsheets heat-welded to one another and gripping the filter material, theassembly thus produced then being subjected to an embossing orcalendering, so as to confine, as much as possible, the filter materialwithin said casing and consequently to optimize the progression of thefluid in contact with said filter material. This casing can be producedfrom any appropriate material which satisfies the conditions ofleaktightness, of resistance to the pressure of a fluid and oftransparency, if appropriate, required. It is, for example, producedfrom plastic, such as from polyethylene, polypropylene, apolyethylene/polypropylene mixture, and the like, and it is capable ofbeing of biocompatible, food or sterile grade, and the like, accordingto the destination and use of the separation device thus formed.

According to another embodiment, the leaktight casing imposing theprogression and the maximum contact of the fluid with the filtermaterial is composed of a single-layer or of a double-layer based on anonwoven or on a textile, coated on one of its faces or receiving, byfilm coating on one of its faces, a PVC or equivalent or laminated witha plastic film, in particular produced from poyethylene sic!. Thissingle-layer or this double-layer thus obtained is wound in the form ofa contiguous or folded spiral, the interturn or interfold spacereceiving the filter material, and the assembly being inserted within aheat-shrinkable sheath, capable of modulating the porosity of thedevice, the rate of passage of the fluid, the separative efficacy, thecompactness of the system and its ullage, and the like, by modifying thewinding pressure or the squeezing of the folds.

In an alternative form of this embodiment, a grid or a drain is insertedbetween the filter material and the leaktight layer or sheath, in orderto promote leaching and movement of the fluid.

The filter material is composed, for example, of a fibrous, filamentaryor cellular material chosen from those conventionally used as filtermedia and in particular activated charcoal, viscose, cotton,polypropylene, asbestos, glass, and the like.

The constituents of this filter material can be negatively or positivelycharged and are capable of undergoing a grafting which confers ionicexchange properties on them (anions, cations, indeed complexing agents),so as thus to create ion exchange textiles, hydrophilic textiles,hydrophobic textiles, and the like.

In a known way, the grafting comprises the development, from a polymer,of various macromolecular chains each possessing several tens or severalhundreds of functional sites which are polar, hydrophobic, hydrophilic,organophobic, organophilic, oxidizing and/or reducing or capable ofattaching an active principle of chemical or biological nature.

The accessibility and the concentration of the sites by grafting resultin kinetics and an efficiency which are better than those obtained todate.

The fibers can be functionalized or functionalizable using afunctionalization agent, such as any appropriate chemical group oractivated arm or arm which can be activated, capable of reacting with aspecific anti-ligand for the purpose of a possible subsequent reactionwith a ligand (or target molecule) capable of being present in a sample.The anti-ligand is in particular chosen in order to form ananti-ligand/ligand complex. By way of example, the complex can be inparticular represented by any antigen/antibody, peptide/antibody,antibody/hapten or hormone/receptor pair, polynucleotide/polynucleotideor polynucleotide/nucleic acid hybrids, or the like.

The functionalization agent can in particular be chosen from alkyl oralkoxy chains or substituted or unsubstituted polyethers which areterminated by a group carrying a reactive functional group. The reactivefunctional group is in particular represented by a functional group suchas a carboxy, hydrazide, amine, nitrile, aldehyde, thiol, disulfide,iodoacetyl, ester, anhydride, tosyl,. mesyl or silyl group and anyreactive functional group capable of reacting with a specificanti-ligand.

The term "polynucleotide" as used in the present invention denotes asequence of at least five deoxyribonucleotides or ribonucleotidesoptionally comprising at least one nucleotide containing a modifiedbase, such as inosine, 5-methyldeoxycitidine,5-(dimethylamino)deoxyuridine, deoxyuridine, 2,6-diaminopurine,5-bromodeoxyuridine or any. other modified base which makes possiblehybridization. This polynucleotide can also be modified at theinternucleotide bond (such as, for example, the phosphorothioate,H-phosphonate or alkyl-phosphonate bonds) or at the skeleton, such as,for example, alpha-oligonucleotides (FR-A-2,607,507) or PNAs (M. Elghomet al., J. Am. Chem. Soc., (1992), 114, 1895-1897). Each of thesemodifications can be taken in combination.

The term "peptide" as used in the present invention means in particularany peptide containing at least two amino acids, in particular proteinor protein fragment or oligopeptide, extracted, separated orsubstantially isolated or synthesized, in particular those obtained bychemical synthesis or by expression in a recombinant organism; anypeptide in the sequence of which one or a number of amino acids of the Lseries is (are) replaced by an amino acid of the D series, and viceversa; any peptide in which at least one of the CO--NH bonds, andadvantageously all the CO--NH bonds, of the peptide chain is (are)replaced by (a) NH--CO bonds, the chirality of each aminoacyl residue,whether it is or is not involved in one or more abovementioned CO--NHbonds, being either retained or inverted with respect to the aminoacylresidues constituting a reference peptide, these compounds being furtherdenoted as immunoretroids; a mimotope, and the like.

A reactive functional group capable of reacting with thefunctionalization agent described above can be introduced at anyposition of the polynucleotide or of the peptide.

The term "antibody" as used in the present application means anymonoclonal or polyclonal antibody, any fragment of said antibody, suchas Fab, Fab'2 or Fc fragment, and any antibody or fragment obtained bygenetic modification or recombination.

Haptens are small non-immunogenic molecules, that is to say incapable bythemselves of promoting an immune reaction by formation of antibodiesbut capable of being recognized by antibodies obtained by immunizationof animals under known conditions.

The base material is provided in the form of a a bed which maybe, amongother things, fabric, of a nonwoven, of a paper, of fibers or offilaments.

The filter material is also capable of being composed of an alveolatematerial, such as foams, sponges, zeolites, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

The way in which the invention can be implemented and the advantageswhich result therefrom will emerge more clearly from theimplementational examples which follow, given by way of information andwithout implied limitation, with the support of the appended figures.

FIG. 1 represents diagrammatically a characteristic device of theinvention, seen from above, of which FIG. 2 is a section along the axisII--II according to FIG. 1.

FIG. 3 is a diagrammatic representation of another embodiment of thedevice in accordance with the invention.

FIG. 4 is a diagrammatic representation of yet another embodiment of theinvention, of which FIG. 5 is a diagrammatic view of the module of FIG.4 represented in an expanded position.

FIG. 6 is a diagrammatic representation of another embodiment of theinvention, of which FIG. 7 is an alternative form.

DESCRIPTION OF THE INVENTION

The separation device in accordance with the invention is representedvery diagrammatically in FIG. 1. This device is composed of twosubstantially rectangular sheets (1) and (2), produced frompolyethylene, tightly gripping a woven fabric, for example composed ofactivated charcoal fibers (3), and abutting onto two pipes, respectivelya pipe for introduction (4) of the fluid to be separated or to befiltered and for departure (5) of the fluid thus separated or filtered.

In a known way, carbon fibers are materials which exhibit advantageousmechanical characteristics, in combination with a low relative density,which makes it possible to use them in the most varied textile forms,such as filaments, fibers, fabrics or braids, which may be two- orthree-dimensional. These fibers are most generally manufactured bypyrolysis of a precursor, in particular based on fibers which arecellulose and which are natural or artificial, indeed synthetic (acrylicfibers). As these carbon fibers are well known, there is no reason todescribe them here in more detail.

The whole periphery of the casing (1, 2) thus constituted gripping thefabric (3) is heat-welded under slight pressure, so that the films (1)and (2) constituting said casing are in close contact with the fibrousmedia (3) and completely welded to the periphery of the fabric, as canclearly be observed in FIG. 2.

By the use of films (1) and (2) produced from flexible polyethylene, theend result is a substantially flat separation profile, as can also beobserved in FIG. 2, capable of deforming with respect to this plane, inparticular folding up or bending, the fabric of the filter material (3)also exhibiting the flexibility capable of adapting to thesedeformations.

In addition, advantageously, the device thus produced is subjected to anembossing or calendering, so as to enable the filter material (3) to begripped as tightly as possible between the two films (1) and (2), so asto preclude or limit any preferential progression of the fluid to befiltered outside the body of the fabric (3) between the introductionconduit (4) and the departure conduit (5), both emerging in the fabric.It is also possible to lengthen the progression of the fluid to befiltered or separated by twists and turns, produced within the casing(1, 2), for example by heat welding, the filter material (3) thenadopting an additional profile.

The pressure exerted during the embossing or calendering depends, on theone hand, on the filter material used and, on the other hand, on thedesired rate and desired efficiency of separation. Of course, thegreater this pressure, the greater the confinement of the filtermaterial (3) within the leaktight casing and, consequently, the slowerthe rate of separation. In fact, it can be advantageous to result in abalance, in order to optimize as far as possible these kinetics ofseparation, without detrimentally affecting, for all that, the desireddegree of separation.

In another embodiment represented in FIG. 3, the filter material isprovided, seen from above, in the form of a U, the introduction anddeparture conduits terminating respectively at the end of the branchesof the U. This embodiment can be used when it is desired to optimize theleaching in contact with the filter material (3) which, this time, is,on the one hand, inherent to the confinement and, on the other hand, tothe path of the fluid in the ascending direction in the second branch ofthe U. It has been observed that this embodiment did not significantlydetrimentally affect the kinetics of separation.

These two embodiments are thus provided in the form of a flat profile,which can optionally be bent, which is entirely capable of beinginserted in an envelope for the purpose of being sent to any place, inthis way enabling on-the-spot or in-line samples to be sent very simplyto places for specific analysis.

In another embodiment-represented in FIG. 4, use is made, as separationdevice, of a device analogous to that of FIG. 1 but which is folded overa number of times on itself in various convolutions, the latter beingkept in contact with one another before use, for example by very weakpoints of adhesion or equivalent. In this way, before use, suchseparation devices have a bulk which is very particularly reduced and,of course, a very low weight. During their use, it is sufficient tosimultaneously pull on both ends, in particular at the introduction anddeparture conduits, in order to free detach the convolutions from oneanother and thus to obtain a separation device which can be useddirectly, after the fashion of that represented in FIG. 1.

Such separation devices, depending on the filter material which theycontain, have multiple applications.

In another embodiment of the invention represented in FIG. 5, the filtermaterial is introduced into a heat-shrinkable or drawable casing, itsvolume being modulated so that, after shrinkage of said casing, theconfinement obtained makes it possible to result in a forced separationunder conditions which are adjustable by the degree of shrinkage.

Another embodiment of the invention has been represented in FIG. 6. Theleaktight casing (1, 2) of the versions described above, the firstfunction of which is to force the fluid to be separated to follow itscourse and to undergo maximum contact with the filter material, iscomposed of a single-layer or a double-layer (10), based on a nonwovenor on a fabric, coated on one of its faces with a PVC or receiving apolyethylene film emplaced by adhesive bonding, in order to confer adegree of leaktightness on it. The casing thus produced is wound arounditself in the form of a spiral, the interturn space of which receivesthe filter material (11), the face rendered leaktight being on theinside of each of the turns, and the central core (12) of which is, forexample, composed of the folding of said envelope (10) on itself or of aPVC axle, to which said casing is adhesively bonded, in order topreclude any preferential progression or passage of the fluid to beseparated.

The spiral thus produced is confined within a heat-shrinkable externalsheath (13) which, depending on the duration of the heating stage towhich the assembly, thus formed, is subjected, is more or less shrunk,thus making it possible to vary both the porosity of the module and therate of passage of the fluid, the separative efficiency or thecompactness of the module.

The module also contains two connecting pieces (14, 15), respectivelyfor introducing the fluid to be separated and for collecting the fluidthus treated. The connecting pieces are flexible and are emplaced on thespiral before confinement by the heat-shrinkable sheath (13).

In an alternative form of this embodiment represented in FIG. 7, thefilter sic! to be separated is supplied tangentially with respect to thespiral (10). In this case, the fluid follows the different concentricturns until it ends at a central drain (16), perforated over its entirelength, situated at the core of said spiral and extending over theentire height of the latter. The two bases of the spiral are thenequipped with compounds which preclude the passage of the fluid at thesepoints, in this way preventing any preferential passage and forcing saidfluid to follow the turns and thus to leach the filter material. Thedrain (16) is in communication with the means for discharge of thefiltered fluid from the device.

The separation device of the invention is capable of a great manyapplications. First of all, in the field of biology, it proves to beentirely appropriate in the context of the inhibition of the bacterialaction of a specific medium.

Thus, the device of the invention is employed for adsorbingantimicrobial agents or inhibitors contained in a biological liquid bypassage in contact with the fabric constituting the filter material,before introducing the biological liquid (such as blood), thus purified,into a flask comprising a culture medium, in order to growmicroorganisms liable to be present.

This application proves to be entirely advantageous in the context ofthe adsorption of antibiotics, three specific examples of which will begiven in detail hereinbelow.

EXAMPLE 1

In this example, the filter material is. composed of a textile fabricproduced from sulfonated polypropylene. The antibiotic tested iscomposed of netilmicin, at a concentration of 40 mg/l, contained in a0.1M phosphated buffer medium at pH of 7.5. 10 ml of antibiotic solutionare injected, using a syringe, into the introduction pipe of theseparation device of the invention and the purified liquid is collectedat the departure pipe.

The antibiotic is then quantitatively determined in the liquid thuscollected according to the conventional agar diffusion technique in aPetri dish. The percentage of antibiotic adsorbed on the filter materialis equal to: ##EQU1## in which the reference value is the measured valueof the buffer medium without separation by the device of the invention.

An adsorption yield of the antibiotic of greater than 99% is obtained.

EXAMPLE 2

The separation of the antibiotic of Example 1 is repeated, this timeusing a cation exchange textile, functionalized with carboxyl groups, asfilter material.

The procedure and the quantitative determination technique are identicalto those described in Example 1.

The result is an adsorption yield in the region of 66%.

EXAMPLE 3

Activated charcoal fibers are used as filter material.

The procedure and the quantitative determination technique are identicalto those described in Example 1.

The test is carried out on different antibiotics in 0.1M phosphatedbuffer solution at pH 7.5.

The results obtained are collated in the table hereinbelow.

    ______________________________________               Netilmicin                        Vancomycin                                  Pefloxacin                                         Amoxicillin    ______________________________________    Concentration in               40       40        20     80    mg/l in the    buffer    solution    Adsorption 95%      70%       90%    95%    yield    ______________________________________

Moreover, the device comprising functionalized fibers on which aregrafted one or a number of specific anti-ligands can also be used todisclose one or a number of ligand(s) in a biological fluid. Theanti-ligand/ligand reaction, if it has taken place, can then berevealed:

either by elution using an appropriate eluent, the eluate obtainedcomprising the anti-ligand/ligand complexes formed, and subsequentvisualization in the eluate by any appropriate tracer (by way ofexample, if the ligand is a protein, the presence of theanti-ligand/ligand complex can be revealed by a labelled antibody, ifthe ligand is a nucleic acid fragment, the polynucleotide/nucleic acidfragment complex can be revealed by a labelled polynucleotide, thesequence of which is complementary to at least a part of the sequence ofthe target nucleic acid fragment but at least partially different fromthe nucleotide sequence of the anti-ligand polynucleotide),

or directly within said device by addition of a tracer as describedabove.

In another embodiment of the invention, the separation device is usedfor the purposes of concentrating a ligand liable to be present in abiological sample. According to the principle described above, theligand is adsorbed on the functionalized fibers comprising a specificanti-ligand of said ligand. An appropriate solution is then passedthrough the device in order to break the bonds established between theanti-ligand and the ligand. The eluate collected comprises only theligand. The action of the concentration of salts or of the temperaturecan in particular be used to elute the ligand. This is applicable inparticular in the field of bacteriology for concentrating microorganismsbefore culturing and in the field of molecular biology for concentratingone or more desired target nucleic acid(s) before a subsequent stagewhich can be, for example, direct visualization as described above or anamplification reaction (for example PCR, NASBA, LCR, and the like) inorder to multiply the number of copies of the target nucleic acid beforedetection.

The device of the invention also finds application in the field of theanalysis of water for revealing pathogenic organisms or trace metals, inaccordance with the principle described above. Once the sample withdrawnhas passed through the device of the invention, the latter can be sentto the analytical laboratory for the desorption stage and analysis ofthe components. In this application, the device, in addition, exhibitsthe advantage of being easy to use in all circumstances and of beingextremely easy to transport.

The device of the invention also finds an application in the field ofchromatography when the fibers are functionalized or functionalizableusing chemical groups, such as quaternary ethylamine ordiethylaminoethyl groups, which confer anion exchange properties onthem; carboxymethyl or sulfopropyl groups, which confer cation exchangeproperties on them; propyl, ethyl, butyl or phenyl groups, which conferhydrophobicity properties on them; C8 or C18 chains, for areversed-phase support; groups inducing metal chelation, thiol groups orthe like.

After the stage of adsorption of the desired compounds, specific elutionbuffers, which are known to the person skilled in the art, are passedthrough the device in order to desorb the adsorbed compounds. The deviceof the invention in this application has a significant advantage in thatit can, after reequilibrating, be used for a new chromatography cycle.

Mention may also be made, among the numerous applications of the deviceof the invention, of the possibility of extracting a species which issoluble in an aqueous medium. To do this, a device in accordance withthat described in FIG. 1 is used. The filter material is composed ofactivated charcoal fibers of 30×70 mm. 50 cm³ of an aqueous methyleneblue solution, with a concentration of 2 mg/l, are injected into theintroduction pipe of the module according to kinetics of 10 cm³ /min.All the filtered liquid emerges colorless.

The identical operation carried out with the same amount of aqueoussolution and with a filter material composed of activated charcoalfibers positioned perpendicularly to the plane of the module results inminimum decoloration; the residual coloration, measured by visiblespectrometry, corresponds to 95% of the initial coloration.

The module in accordance with the invention is also capable of beingused in the context of concentrating trace components and ultratracecomponents. Thus, the continuous filtration through a module of theinvention comprising an IET (Ion Exchange Textile) makes it possible toresult in a concentration of the trace components which it is desired todetect, up to the detection thresholds which can currently be used.Indeed, the detection of heavy metals proves to be impossible withconventional means for automatic monitoring when their concentration isless than the ppb level.

With the module in accordance with the invention, it thus becomespossible to detect the existence of hexavalent chromium present at theppb level in a fluid containing trivalent chromium. The filter materialis an IET carrying quaternary ammonium groups, sites which are stronglycationic ion exchangers.

Other applications can also be envisaged by means of the module of theinvention. Mention may be made, for example and without impliedlimitation, of:

the extraction of traces of toxins in an industrial process: theselection of the filter material makes it possible to fix traces ofnickel in electroplating effluents in order to reach the regulatorydischarge threshold;

the recovery and the purification of proteins: in production,preservatives based on heavy metals are used, which it is advisable toremove without degrading the proteins. This removal is made possible bymeans of the module of the invention, the filter material of which iscomposed of a cation exchange textile support;

the concentration of β-emitter radioactive elements: said elements arefixed to an appropriate filter material and protected by the confinementcasing produced from polyethylene. This casing makes it possible tohandle the module by direct contact in order to render safe all thehandling and dispatching operations and the like;

the combination of modules providing different functionalities makes itpossible to define, in a single operation by selective analysis which iscarried out subsequently, the medium or media, their family and theseparative techniques which are appropriate.

Mention may be made, among the various advantages provided by such adevice, of:

the possibility of having available a tool which is very simple to use,which is flexible and which is capable of thus allowing analyses andmeasurements to be carried out in-line and continuously;

the possibility of carrying out separations according to optimizedkinetics, without, for all that, having a detrimental effect on theresults and the quality of said separations;

the possibility of carrying out, at least cost, any type of simulationin the field of separation techniques and consequently of validating aseparative treatment, whatever its stage of development;

the possibility of having available a simple and inexpensiveconcentration or separation system for diagnosis or with analyticalpurposes;

such a device can be easily rendered tamper-proof and can be dispatchedby conventional forwarding means (post and the like);

the possibility of easily designing the device as a function of thecharacteristics of the fluid to be treated;

the possibility of easily interconnecting various modules of differentfunctionalities;

in addition, taking into account its very structure, such a separationdevice is easy to sterilize but also convenient to remove from a wastetreatment device (indeed, can be simply discarded) or can be regeneratedin the context of the use of ion exchange textiles as filtrationmaterial;

moreover, due to the low ullages, the exchanges between the fluid to befiltered and the filter material take place under the best conditions.

In fact, such devices are very particularly suitable in conjunction withdiagnostic tools or conventional components for separation,purification, decoloration, immobilization, filtration or retention.

We claim:
 1. Apparatus for the physicochemical separation ofconstituents of fluids that includesa flexible leak-tight orsemipermeable casing made of plastic which tightly envelopes a filtermaterial to form a filter having or capable of adopting a flat profile,an inlet pipe for introducing a fluid into said filter, an outlet pipefor discharging said fluid from said filter whereby separation andfiltering of the fluid takes place in the plane of the filter and withrespect to the flat profile of the filter material, said casing beingfolded to form convolutes that contact each other at contact points andan adhesive means at said contact points for attaching the convolutestogether prior to use, and said adhesive means having a bonding strengthsuch that said convolutes become detached by the introduction of a fluidinto said casing.
 2. Apparatus for the physicochemical separation ofconstituents of a fluid that includesa pair of flexible leak tight orsemi-permeable flat films that are joined along their outer peripheriesto form a flat envelope lying within a plane, said envelope beingcompletely filled with a flat bed of filter material for physicochemicalseparation of constituents of a fluid, an inlet pipe having an axislying within said plane of the envelope for introducing a fluid into oneend of said envelope, perpendicular to one edge of said bed, an outletpipe having an axis lying in the plane of said envelope for dischargingsaid fluid from the opposite end of said envelope wherein said fluidflows in contact with said bed of filter material along the entirelength of said bed.
 3. The apparatus of claim 2 wherein said films areplastic sheets that are heat welded together to tightly compact thefilter material within the plane of said envelope to optimize contactbetween the fluid and the filter material.
 4. The apparatus of claim 3wherein said films are U-shaped sheets that are joined together to forman envelope having a pair of adjacent legs, and said inlet pipe beingconnected to one leg of the envelope and said outlet pipe beingconnected to the opposite leg of said envelope.
 5. The apparatus ofclaim 3 wherein said films are formed of a heat shrinkable material thatis shrunk to tightly pack the filter material within said envelope. 6.The apparatus of claim 2 wherein the films are formed of a non-woven ortextile material having a polyethylene coating upon one face thereof. 7.The apparatus of claim 2 wherein the film are formed of a materialselected from the group consisting of biocompatible polyethylene orpolypropylene.
 8. The apparatus of claim 2 wherein said filter materialis selected from any one of a group of materials that consist of fibrousfilamentary cellular or alveolate materials.
 9. The apparatus of claim 2wherein said filter material has constituents that are flnctionalized bygrafting to confer ionic exchange properties thereto to create ionexchange textiles, hydrophilic textiles or hydrophobic textiles.
 10. Theapparatus of claim 2 wherein said filter material is selected from thegroup consisting of activated charcoal, asbestos, glass fibers, viscosecotton polypropylene, foam sponges and zeolite.